Digital imaging is an increasingly popular form of scene capture and image or photographic print rendering. One reason for this popularity is the ease with which users can manipulate, edit, alter and enhance such digital images. For example, users often use manual digital imaging and editing tools that allow a user to select a limited portion of the captured image that is to be enlarged, using digital interpolation techniques, to the same size in the rendered image, photographic print, or electronic display as would have been rendered if the entire captured image had used. This process is commonly referred to as “digital zoom”. Since the interpolation techniques of the digital zoom process effectively spread a lesser amount of data over the same rendered image size as would have been produced from the entire captured image, the image resulting form the digital zoom process has a reduced image resolution as compared to the same sized image produced data taken from the entire captured image.
Often, the digital zoom functions is performed using image processing systems such as cameras, personal computers, kiosks, personal digital assistants, network centric systems, other devices. These devices generally have a display for presenting a digital image and some form of user interface to permit a user to designate a selection area, commonly the central area of the image, for use in forming a zoom and crop processed image. In some digital cameras, a graphical indicator may be provided to advise the camera user that digital zoom selection is in operation. However, such arrangements do not always advise the user of whether a particular selected digital zoom setting will result in a satisfactory resolution in the rendered image. Digital zoom setting is usually expressed as a digital zoom ratio where a zoom ratio of 1.0× corresponds to minimum or no zoom and higher ratios correspond to higher amounts of zoom enlargement. In U.S. Patent Application Publication 2003/0117511, an attempt to warn a camera user of the effect of the zoom ratio selection on appearance quality of the to-be rendered image or print is provided in the form of text or graphical indicators (icons) that suggest that lowered image resolution (or print satisfaction) may result with increasing zoom ratio selection. However, such warnings have the disadvantage that they are passive, in nature, and can be easily overlooked and ignored during the image composition process.
In more sophisticated systems, the digital image data contained the selection area may be processed during image composition using the digital zoom setting to form a processed evaluation image ostensibly as it would appear in the ultimate rendered image. In this case, users often rely upon the appearance of the evaluation image as presented in the display in order to determine whether the zoom and crop processed image represented by the evaluation image has a preferred appearance. Where the evaluation image has an acceptable appearance, users will often elect to store the zoom and cropped processed image, or use a printer or like device to render the zoom and cropped processed image on a film fabric or paper. However, the limited display resolution of conventional electronic displays and, in particular, small sized displays of the type commonly used in conjunction with digital cameras can mask the loss of resolution in a zoom and crop processed image. Accordingly, users can designate a selection area that comprises only a fraction of the original image without realizing that such aggressive use of the zoom and crop algorithm can reach a point where so much of the data comprising the originally captured digital image has been discarded that the zoom and crop processed image does not have a minimum amount of data necessary for the rendered image of given size to have an acceptable level of image quality (resolution).
Commonly assigned U.S. Pat. No. 6,018,397, entitled “Digital Image Processing With Indication to User of Hardcopy Output Image Quality”, issued Jan. 25, 2000 by Cloutier et al. describes a digital image processor that establishes a boundary level of acceptable hardcopy print quality level based on selected image print size and printing magnification and provides a warning to a user prior to generation of the hardcopy print that alerts the user when the determine print image quality will be unsatisfactory. This system receives inputs including digital image data representative of an image to be reproduced in hardcopy at a user-selected size, hardcopy image quality information being representative of acceptable and unacceptable levels of hardcopy image quality produced with said hardcopy image reproduction and information representative of the desired magnification and user selected size of the hardcopy image to be output and indicates whether this combination will generate images having an acceptable appearance. The '397 patent provides a warning to a user when the user selects a combination that may not yield acceptable results prior to submitting the image for hard copy image formation. While useful and commercially valuable, this approach requires a user to designate a selection area within the image and indicate a desired output before providing the warning.